Orgasm Onset as a Threshold Transition: When Bottom-Up Signals Override Control Without Collapse

Masters and Johnson (1966) distinguished plateau from orgasm as a qualitative transition marked by loss of voluntary control and reflexive discharge rather than gradual intensification of arousal. However, the neural mechanism underlying this abrupt shift remains unclear. This paper proposes that orgasm onset is a threshold transition defined by a calibrated inversion of hierarchical control, in which bottom-up interoceptive signals transiently dominate over top-down inhibitory regulation while preserving system-level coordination. As interoceptive excitation accumulates within an affective–embodied predictive hierarchy, inhibitory precision relaxes until a critical boundary is reached, producing irreversible commitment to coordinated autonomic–motor discharge. Comparison with epileptic seizure onset clarifies this mechanism. Both involve escalation followed by rapid convergence, but they diverge in regulatory precision: seizure reflects runaway hypersynchrony, whereas orgasm reflects temporally bounded, coordinated integration. Clinical observations of orgasm-associated seizures further demonstrate that escalation can, under conditions of impaired inhibitory precision, exceed regulatory containment and transition into propagative instability. This contrast identifies regulatory calibration as the key parameter governing threshold outcomes. Orgasm onset is therefore not the peak of arousal but a reorganization of hierarchical control at the edge of instability, with implications for threshold transitions across biological and cognitive systems.